The proposed work seeks to use the Surveillance Epidemiology and End Results-Medicare and Texas Cancer Registry-Medicare linked databases to analyze claims data to evaluate radiation therapy utilization and costs at the end of life as well as the use of advanced radiation therapy technology at the end of life. The specific advanced radiation techonology to be studied will be intensity modulated radiation therapy (IMRT) a complex and expensive modality without proven palliative benefit, despite the fact that investigators have found that 57% of radiation oncologists use this modality for palliation. This grant will perform analyses of claims data using diagnosis and procedure codes to use the claims data to ascertain what may represent over-aggressive radiation therapy treatment at the end of life for cancer patients with the five most common causes of cancer death in the United states (breast, colorectal, lung, pancreatic, and prostate cancers). The specific aims are: 1) to assess the utilization (i.e., proportion receiving), intensity of utilization (i.e., number of treatements) of radiation therapy in the last 30 days of life, and costs as well as socio-demographic and health services factors that may be associated with radiation therapy receipt in the last 30 days of life; and 2) to explore the trends in IMRT utilization among cancers patients receiving radiation therapy in the last 30 days of life. Regression models will be used to determine socio-demographic and health services characteristics that may be significantly associated with receipt of radiation therapy or IMRT at the end of life. Currently, there are no data from U.S. cohorts reporting on RT utilization and advanced radiation therapy technology diffusion, such as IMRT, at the end of life. Thus, this proposed work would provide unique, population-based data regarding end of life care for elderly patients in the U.S. Long-term objectives include establishing data and methodology to serve as preliminary work toward a larger R-01 study proposal to employ claims data to analyze the costs and cost effectiveness associated with radiation therapy utilization and advanced radiation therapy technologies at the end of life for cancer patients.